In this paper, we present two new fuzzy inner product spaces and investigate some basic properties of these spaces. Specially, we prove parallelogram law for two and three vectors. Also, we introduce a suitable notion of orthogonality.
Ehsan Mostofian. Mahdi Azhini. Abasalt Bodaghi. "Fuzzy inner product spaces and fuzzy orthogonality." Tbilisi Math. J. 10 (2) 157 - 171, Feb 2017. https://doi.org/10.1515/tmj-2017-0034